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Enging Run On -


snomobeelr

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  • 2 weeks later...

Cat has been running vince since changing plugs. I finally changed out the jets from 76 to 73. I tried readjusting the 4 corner screws after she warmed up but its the same that way. It likes to be out 2 full turns. When I got to 1.5 she drops. Only difference I noticed was the idle seemed a little lower when in gear. If I shut it down in park I still get a little run on.  Other thing I was thinking was the Power valve. My vacuum is 12 in park and about 6 in gear. If the power valve is supposed to b half of the vacuum reading in gear it should be 3.5 Power valve correct? I believe the one in there is a 6 or 6.5. 

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Haven't tried the race fuel. Ill do that next, but I just filled up so Ill have to burn some out. I looked it up and there is a place not to far that has"Sunoco Fuels: GT 100  I ll try that next. I was just wondering if the power valve had anything to do with the reason the 4 corner screws are 2 turns out.  Also wondering if I should run carb cleaner through the engine while running engine to clean anything off in cylinders or is that a bad Idea?  She is running good, and I am fine with shutting her down in gear so I don't get the run-on. But I am going to try the racing gas next chance I get.  

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the power valve does not effect the idle, it only effects main metering

 

my idle vacuum in gear is 9", I run a 8.5 power valve and may change to a 10.5, don't believe all the BS about power valves, it enriches the main metering circuit and has nothing to do with the idle circuit

 

I've seen your posts at Pro-Systems, as by what we have talked about, fuel is the next thing, you could retard your BASE timing about 4-5 degrees and reset the idle to see if that helps but I think you have more compression than you think, mine will run-on if I use mid-grade 89 octane, put 93 back in it and it goes away

 

listen to what Patrick @ Pro-Systems told you

 

I am waiting for my new carb from him to show up cause this Quick Fuel 750 I have has always given me trouble at light throttle/cruise no mattter what changes I make to it

 

my new carb is based on a 950 HP, it will flow approx 830-840 CFM

 

I just re-read your post @ Pro-Systems, try your idle screws at 1 3/4" turns out, a 1/4 turn on a 4 screw idle system is a lot and by looking at your carb build sheet, I am getting almost the same carb as you, my engine is very close to yours except you are running alum heads

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Afraid my wife is right. I don't listen/read Well.  I went this morning added 6 gallons  "Yikes" $43.00  smackers - of 100 octane race fuel and topped off with the 93.  I thought maybe I was imagining it but after 10 mies when I came to some stop lights she seemed to be idling better/smoother - really good. Took a long drive out to my cousins.  Long is 55-60 miles round trip. She seems to run better at 55 to 65 too. Almost seems like the RPM were a little lower at the higher speed than before. Again maybe in my head. My temp stays between 180 and 185 did this previously as well unless really hot would go to 190. .I have only shut it off twice and she was hot and No run on.   I 'll take her out later for some more testing/fun cruising. Another dumb question. Could I use Octane Boost instead and if so What kind. Thanks for all the help and the patience with me.

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if it was mine...first I would try to take some timing out of it to see if you can get by with straight 93

 

I have no suggestions for octane booster, maybe try cutting back the mix to 3 gallons to a tank of 93 and see how it does

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you are only getting 14 degrees of mechanical advance?

 

I think you said you had 18 degrees of base (initial) timing?

 

we maybe hitting on something here...

 

I would try 14 degrees of initial, and a smaller bushing for more mechanical, but when you set the initial (with the vacuum advance disconnected) turn your idle down as far as you can and still keep it running, if you don't...sometimes the mechanical advance has already started (mine starts around 800 rpm)

 

the reason why I am asking you to re-due your timing...is you said you have 38 degrees, so if that is correct and you are using a 14 degree bushing, you have 24 degrees of initial AND THAT! could be the cause of your run-on

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Correct,  right now I have timing set to 18 initial.  I went and looked at the Kit I sent with the distributor when I had it degree'd I should have paid more attention. Looks like he swapped the bushing; One missing in the kit is the Blue = 21. The 14 - Bushing is in the kit. Ill have to pull the distributor to see what is defiantly in there.

So If the  Blue-21 is in there and I have Initial set to 18 thats 39 total correct? Or am I messing that up?

Previously I attempted to lower the Initial timing and raise the idle it would be ok in park but want to die when put into gear. 

 

Bushing           Crankshaft degrees

Red-Smallest               28

Silver                           25

Blue                             21

Black-Largest              18 

4-secondflat                 14 

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So I backed the Timing to 12 and it just wants to die when I go from park to drive. I put it up to 14 and it is a little better than 12 but had to feather it a little when in drive so it didn't die. I took a video of it and attached it. The second time I shut her down there was a hint of run on. 

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So I pulled the distributor and the bushing. The bushing that is in the distributor is black, same size as the one in the kit. Thats what I get for assuming. So I do not have the Blue - 21 bushing. 

 

 

 

Bushing           Crankshaft degrees

Red-Smallest               28

Silver                           25 

Blue                             21 

Black-Largest              18 

 

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So Like you said Il just have to use some racing fuel. I was thinking I could change to the Blue bushing which is 21. But that will not change what  my initial timing should be at.. That would just change my centrifugal timing and put me at 39 for Total Timing Correct ?  There is the 14 - bushing but it dosent fit correctly so I wont bother with that. 

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 I am overthinking things.  I now Know I have the Black-18 Bushing in the distributor. So I set  inital timing to 18 and total is 36..  I am setting my timing with the Vacuum advance Disconnected/plugged. My timing tab is only numbered up  to 16 and I am thinking the end of the tab is 18. I have been setting it by the line that goes across the entire balancer that is forward of the "0" Mark , see picture. That line is a tick past the End of the tab - That is where I set my Initial. I am thinking that is "18".  When I set the total I thought the 36 mark on the balancer was supposed to line up to "0" on the timing tab. i just want to verify I have this correct.

 

Since I will have to run some Racing fuel anyhow, should I try to find a smaller 14 bushing and try more advance. Or am I at the max advance I should be at. 

 

 

post-44-0-78061900-1471575329_thumb.jpg

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  • 1 year later...

Update :  So I ended up mixing  4 to 5 Gallons of "100 - Octane" with a tank of gas and I do not get the run on.  I have gone without a doing the mix and it is actually not as bad as it was.  So somtimes I do not do the Mix and just  shut her down in Drive. I also added a PCV valve and now I do not have the oil all over the back of the carburetor and I do get better vacuum.  So I have been driving the car all summer. I have about 1500 miles on the plugs . They look much better than in the beginning when I started this post.  I attached Pictures of the plugs now. Better but still seem a little sooty.  

 

 

post-44-0-44731800-1507588318_thumb.jpg

post-44-0-42717800-1507588442_thumb.jpg

post-44-0-52715300-1507588494_thumb.jpg

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